Your looking at big bucks
you need a
SSL connect from your computer to the bank
(This is special APM connection --I belive)
About 1500 bucks a year I hear....
You need a SSL connection from your server to the clients machine
anywhere from 125 to 500 a year
so total 2 ssl connections
you need some type of e commer shopping cart..
To sell items....
If you can do database design you can use paypal for the top APM connection to the bank.
but you paypal like a 2.2% on every transaction... and 30 cents